Overweight and obese are conditions defined as abnormal or excessive fat accumulation that may impair health. It results from imbalances in the body's regulation of energy intake, expenditure and storage.
Obesity is one of the greatest public health challenges of the 21st century. It is a complex condition, one with serious social and psychological dimensions, that affects virtually all age and socioeconomic groups in both developed and developing countries. The health consequences of obesity range from increased risk of premature death to serious chronic conditions that reduce the overall quality of life. Excess weight is the fifth leading risk for global deaths. At least 2.8 million adults die each year as a result of being overweight or obese. In addition, 44% of the diabetes burden, 23% of the ischaemic heart disease burden and between 7% and 41% of certain cancer burdens are attributable to being overweight or obese.
Among the reasons that have led to the dramatic increase in obesity are an increase in the intake of high fat, salt and refined sugar foods that are energy rich but otherwise low in nutritional value (vitamins, minerals, micronutrients) in combination with an increasingly sedentary nature to everyday life with a dramatic decrease in physical activity.
Prebiotics have attracted interests as candidate compounds for the control of obesity and associated metabolic disorders. In animal studies, prebiotics have been shown to regulate the intake of food, prevent weight gain, beneficially alter lipid metabolism and reduce obesity-related inflammation. So far, most studies have focused on simply supplementing the diet with inulin and fructooligosaccharides (FOS).
Prebiotics are dietary ingredients which can selectively enhance beneficial indigenous gut microbiota, such as lactobacilli or bifidobacteria, and are finding much increased application into the food sector. Prebiotics are non-digestible food ingredients that are selectively metabolised by colonic bacteria which contribute to improved health. As such, their use can promote beneficial changes within the indigenous gut microbial milieu and they can therefore help survivability of probiotics. They are distinct from most dietary fibres like pectin, celluloses, xylan, which are not selectively metabolised in the gut. Criteria for classification as a prebiotic is that it must resist gastric acidity, hydrolysis by mammalian enzymes and gastrointestinal absorption, it is fermented by intestinal microflora and selectively stimulates the growth and/or activity of intestinal bacteria associated with health and well-being.
One of the primary functions of the colonic microbiota is to salvage energy from dietary material that has not been digested in the upper gastrointestinal tract, through participating in the initial hydrolysis of complex macromolecules, breaking them down into smaller fragments that can be utilised by other members of the gut microbiota. It is postulated that about 7% to 10% of the total daily energy requirements of the host are derived from colonic bacterial fermentation. In the absence of microbial fermentation in the gut, this energy contribution to would be lost to the host, as humans lack the enzymes necessary to catabolise plant polysaccharides and they would be excreted from the organism as waste. As such, it appears that the presence of a gut microbiota may lead to a direct increase in energy salvaging through the fermentation of dietary polysaccharides.
Although obesity is caused by an excess caloric intake which is not matched by an increase in energy expenditure, differences in gut microbiota composition and activities between individuals may also be an important contributing factor affecting energy homeostasis. This would imply that the gut microbiota of obese individuals would be more efficient in salvaging and/or storing energy from a specific diet compared to the microbiota of lean individuals.
Some dietary fibres can form viscous gels on exposure to an aqueous environment and their gelling properties may account for weight loss promoting effects by delaying gastric emptying, slowing bowel transit time and blunting post-prandial surges in insulin and glucose.
The texture of yoghurt may be modified by using strains of lactic acid bacteria which produce exopolysaccharides. Exopolysaccharides can increase the viscosity, thickness, stability and gel firmness of fermented milk products, including yoghurt. Exopolysaccharides may increase the viscosity of fermented milk products by interacting with milk proteins. The production of exopolysaccharides by the lactic acid culture can reduce the need for bio-thickeners or additional fat to increase the viscosity of the fermented milk product. Hydrocolloids of plant origin have been used to stabilise the gel structure of yoghurt. Many of these hydrocolloids are chemically modified or extracted using various chemicals. As their use is restricted in some countries, there is a need to identify alternative texture modulating agents.
Consumers increasingly demand products with reduced fat and/or sugar content and minimal additives. Using bacterial strains which secrete the desired exopolysaccharides reduces the need to add additional fat to increase the viscosity of fermented milk products. Exopolysaccharide producing strains also reduce the need to add additional sugar, stabilisers and thickeners. As less additional ingredients are needed to achieve desirable sensory characteristics production costs can be reduced.
There is also motivation to increase the viscosity of food products to increase satiation for consumers. Increased satiation can aid those on calorie controlled diets. Food products with a thicker texture may also have a slower transit through the gastrointestinal tract so prolonging the feeling of satiation. Furthermore, food products which also form complexes or impede digestion of food products during digestive transit are also believed to increase the feeling of satiation. Satiation is an important element for controlling food intake and can be used in weight management to discourage eating too much food and/or too regularly.
A food product with a thicker texture may also be useful for the suspension or incorporation of additional ingredients throughout the food product. This is often hard to achieve with food with low viscosity consistency or low fat content.
Many studies have shown that the amount and properties of the exopolysaccharides secreted by bacteria are strain dependent. Exopolysaccharides derived from Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus have shown large variation in composition, charge, spatial arrangement, rigidity and ability to interact with proteins. No defining correlation between exopolysaccharide concentration and viscosity of the food product has yet been established.
It is an object of the present invention to provide a formulation which can be used for weight management—whether included as a food stuff or added to food. It is a further object of the present invention to provide a formulation whose components have a synergistic effect on an individual so as to reduce or modulate weight gain. It would be preferably if such a formulation was effective in more than one area of weight management, for example modifying metabolism of fat and reducing energy gain by colonic bacterial fermentation. It would further be preferable to provide a formulation which enhances satiation. It would also be preferable that the formulation could be easily consumed as either a manufactured foodstuff or an additive which could be added to foods.